Will the MD-80 Save AA?

[Bob Owens]

With the Chem etch failure on the 757 a few months back, the recent 5 foot blowout on Southwest and the news that many 757 and 737s are turning out to be 15 year planes instead of 25 year planes could it end up that the gas guzzling MD-80s may be AA's greatest assett?

 

[TWU informer]

Not likely. T-Cap Bulk Head cracks at Heavy C6, Wing Root cracks at heavy C6, and Guzzling Gas not a real powerful option compared to crown skin cracks and engines that last twice as long on wing as JTD8's.

Might be that in-house overhaul saves AA but only because of control over correcting these problems and quick mobilization.

Everyone in Tulsa knows the MD-80 has problems too, just not in the news and in the public view right now.

 

[WorldTraveler]

I wouldn't go that far... but the DC9 is one of the most durable aircraft in the skies... I'm not sure that some of that durability was lost as the DC9 was stretched... and it also says that having a diverse fleet of aircraft is one of the best hedges against a particular problem that couple cripple a large part of the fleet.
The A320 doesn't look so bad against the 737 now and everyone already knew that the 320s weren't intended to be as long-lived as what we are finding might be the reality for the 737 after all.

 

[eolesen]

When you push high utilization on anything mechanical, you're going to wind up with structural issues. The number of cycles on some of WN's 737-300s exceeds what anyone else has achieved, so it's a bit sensational to try and draw the conclusion that other carriers are going to see the same flaws emerging at the same point in age.

Question for the structures guy... how realistic is it to replace chem etched with machine milled during an overhaul?

 

[FWAAA]

Do the NG 737s (737-700s and 737-800s) in wide use at AA and DL share the potential defects that have arisen in WN's 733s?

 

[tech2101]

When you push high utilization on anything mechanical, you're going to wind up with structural issues. The number of cycles on some of WN's 737-300s exceeds what anyone else has achieved, so it's a bit sensational to try and draw the conclusion that other carriers are going to see the same flaws emerging at the same point in age.

Question for the structures guy... how realistic is it to replace chem etched with machine milled during an overhaul?

It would be very easy to just install doublers over the suspect areas.

We did the DC-9 Crown Repair doublers, window belt doublers, L/G attach fittings, main frame upgrades, APB mods, etc... and saved NWA a ton of money by keeping those flying.

I would say LUV would be a good candidate for an 737 aging aircraft program like NWA used on its DC-9's.

 

[Veritas]

Do the NG 737s (737-700s and 737-800s) in wide use at AA and DL share the potential defects that have arisen in WN's 733s?

The 737NG uses a different lap-joint design than the older models.

MarketWatch - Boeing: hundreds of older 737s at risk for cracks

"The cracks that led to a Southwest 737-300 jet losing a part of its fuselage while in mid flight last week radiated from lap-joint fasteners that hold pieces of the outer skin together, said Paul Richter, chief project engineer for the 737 jets built before 2000.

"Such stress cracks were anticipated, but not before the jets had performed at least 50,000 flights.

<snip>

"The early cracking of the 737 fuselage should not occur in later 737 models, Richter said.

"The current model in production, 737NG, uses a different lap-joint configuration to fasten parts of the fuselage skin that limits the joints’ bending during pressurization, which is what leads to stress, metal fatigue and eventually, cracking, he said."​

 

[Bob Owens]

It would be very easy to just install doublers over the suspect areas.

We did the DC-9 Crown Repair doublers, window belt doublers, L/G attach fittings, main frame upgrades, APB mods, etc... and saved NWA a ton of money by keeping those flying.

I would say LUV would be a good candidate for an 737 aging aircraft program like NWA used on its DC-9's.

There goes the weight/fuel savings. What a lot of people are forgetting is that this is at least the third failure we've seen in the last couple of years. Southwest had two.

 

[BoeingBoy]

There goes the weight/fuel savings.

Not really. Adding some 20-30 pound doubler's doesn't make that much difference on an 80,000 pound airplane. And the problem so far appears to be restricted to 1993 and later Classic 737's - a relatively small number of planes out of all those built.

Jim

 

[Interested]

Not really. Adding some 20-30 pound doubler's doesn't make that much difference on an 80,000 pound airplane. And the problem so far appears to be restricted to 1993 and later Classic 737's - a relatively small number of planes out of all those built.

Jim

Those 20-30 pound doublers must make some difference if they are replacing food service with lighter weight one to save a few pounds.

 

[Frank Szabo]

Those 20-30 pound doublers must make some difference if they are replacing food service with lighter weight one to save a few pounds.

I suggested, many years ago, a contest be held to guess the "after" weight of a 727 after having their tons of doublers installed over the years - the management person I said that to didn't think it was a good idea, to say the least.

 

[Frank Szabo]

The 737NG uses a different lap-joint design than the older models.

MarketWatch - Boeing: hundreds of older 737s at risk for cracks

"The cracks that led to a Southwest 737-300 jet losing a part of its fuselage while in mid flight last week radiated from lap-joint fasteners that hold pieces of the outer skin together, said Paul Richter, chief project engineer for the 737 jets built before 2000.

"Such stress cracks were anticipated, but not before the jets had performed at least 50,000 flights.

<snip>

"The early cracking of the 737 fuselage should not occur in later 737 models, Richter said.

"The current model in production, 737NG, uses a different lap-joint configuration to fasten parts of the fuselage skin that limits the joints’ bending during pressurization, which is what leads to stress, metal fatigue and eventually, cracking, he said."​

The simple fact the failure was as straight as it was suggests to me it was caused by a shearing action, similar to scissors. One piece of AL skin (the failed part) had to be forced against another acting as a die (non-moving part) by the internal pressure (punch component) to make the straight "cut", if you will.

This type of "Failure in progress" would have a coined (displaced metal, slightly rolled boundary) edge very near the failure area.

 

[BoeingBoy]

I suggested, many years ago, a contest be held to guess the "after" weight of a 727 after having their tons of doublers installed over the years - the management person I said that to didn't think it was a good idea, to say the least.

I agree with older planes. PI/US had some old 737-200's that had doublers all over them. However, here we're talking about new planes replacing the MD80's, which aren't that old themselves - nothing like the NW now DL DC9's. I would guess that even with the MD80's there aren't enough doublers to significantly affect the weight or fuel burn.

Jim

 

[777 fixer]

With the Chem etch failure on the 757 a few months back, the recent 5 foot blowout on Southwest and the news that many 757 and 737s are turning out to be 15 year planes instead of 25 year planes could it end up that the gas guzzling MD-80s may be AA's greatest assett?

How exactly is the MD-80 going to "save" AA? If AA were to ground all the 757's tommorow you would not be able to put MD-80's on a lot of those routes since they do not have the capability to fly them. And it's not like you have dozens of them sitting around waiting at a moments notice fo the routes they could fly.

Don't get me wrong. the MD-80 is a good aircraft. However it's days in airline service are numbered.